What causes Polyarteritis nodosa?
Unknown. An immune complex-mediated mechanism is frequently considered, but immune complex deposits or complement components are seldom found in involved vessels.
Direct endothelial injury with subsequent release of cytokines and mediators of inflammation is another theory, but the triggering factor or antigen has not been found. Several conditions have been associated with PAN or PAN-like vasculitis, including:
• Viral infections (e.g., HBV > cytomegalovirus, human T-lymphotropic virus 1, HIV, parvovirus, Epstein–Barr virus, hepatitis C [rare]).
• Autoimmune disorders (e.g., systemic lupus erythematosus [SLE], rheumatoid arthritis, childhood dermatomyositis, Cogan’s syndrome).
• Genetic: recessive loss of function mutation of adenosine deaminase 2 (: Juvenile Systemic Connective Tissue Diseases).
• Medication reaction (e.g., allopurinol, sulfa).
• Hairy cell leukemia.
